Revision: 12479
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at March 16, 2009 13:05 by allnatural
Initial Code
//
//
// Initial variables.
var pendX = 250;
var pendY = 250;
var pendRadius = 200;
var pendArc = 135/360;
var pendSpeed = .005;
var pendCount = 0;
//
//
//
// Make a red footbal-shaped clip.
createEmptyMovieClip("Pendu", 10);
with(Pendu){
beginFill(0xFF0000);
moveTo(-20, 0);
curveTo(0, 15, 20, 0);
curveTo(0, -15, -20, 0);
}
//
// Make a clip in which to draw the stick holding the pendulum.
createEmptyMovieClip("Stick", 5);
//
//
//
// Swing a point on an eased arc with the given properties.
function pendulum (centerX, centerY, radius, aoi, completionRatio){
//
// Use magic trig function to turn linear values between 0
// and 1 to eased values between -1 and +1.
var easedOneToNegOne = Math.cos(completionRatio*2*Math.PI);
//
// Convert "Angle Of Inclination" from a ratio between 0
// and 1 to radians.
var aoiRadians = aoi * 2 * Math.PI;
//
// Determine eased rotation of the pendulum in radians.
// Derived from #3 in the above "Conventions" section.
var currentRotation = easedOneToNegOne * aoiRadians;
//
// Get X and Y coordinates of pendulum at eased angle of rotation.
var x = centerX + Math.sin(currentRotation) * radius;
var y = centerY + Math.cos(currentRotation) * radius;
//
// Return both X and Y coordinates inside a single 'point' object.
return {x:x, y:y};
}
//
//
//
// Advance the pendulum to its next position.
function swingPendulum (){
//
// Increment the clock counter.
pendCount += pendSpeed;
pendCount %= 1;
//
// Get the pendulum's new coordinates.
var point = pendulum (pendX, pendY, pendRadius, pendArc, pendCount);
//
// Place the pendulum at its new coordinates.
Pendu._x = point.x;
Pendu._y = point.y;
//
// Draw a line from the center to the pendulum.
with (Stick){
clear();
lineStyle(2, 0);
moveTo(pendX, pendY);
lineTo(point.x, point.y);
}
}
//
// Keep Swinging the pendulum every time we enter a frame.
onEnterFrame = swingPendulum;
//
//
//
//
Initial URL
http://www.pixelwit.com/blog
Initial Description
Initial Title
Swinging Pendulum
Initial Tags
Initial Language
ActionScript 3